Restriction Requirements, Double Patenting, And Finding The Safe Harbor

Restriction requirements under 35 U.S.C. § 121 arise during examination at the U.S. Patent and Trademark Office (USPTO) when an examiner determines that an applicant is pursuing multiple, patentably distinct inventions within the same application.  The examiner's determination, however, may not always be in agreement with that of a court.  In litigation, an accused infringer may assert that the patentee pursued the same or obviously similar inventions in multiple applications, one or more of which later issued as the patent-in-suit.  A finding of double patenting can invalidate the offending claims.  To account for this possible anomaly, 35 U.S.C. § 121 includes a safe harbor against double patenting, whereby "[a] patent issuing on an application with respect to which a requirement for restriction under this section has been made, or on an application filed as a result of such a requirement, shall not be used as a reference . . . against a divisional application or